Data-Driven Sensor Placement for Nuclear Reactor Transient Analyses in Digital Twins

Analyzing the effect of transients on reactor core coolant temperature, pressure, and velocity is essential for real-time safety monitoring and control of a nuclear reactor. The strategic placement of sensors critically enables reconstruction of latent reactor flow fields from sparse, heavily constrained measurements. We develop a data-driven optimization procedure for sensor placement that leverages reduced order models (ROMs) of flow physics, including dynamic mode decomposition and autoencoders. These ROMs help reveal the underlying dynamics and behavior of complex nuclear systems, with the goal of constructing a digital twin of the target nuclear asset. The developed methodology is also extended to determine optimal sensing locations and time steps for collecting sparse measurements. The effect of different ROMs on sensor locations and flow reconstruction performance is demonstrated on the Out-of-Pile Testing and Instrumentation Transient Irradiation System (OPTI-TWIST) prototype, which is electrically heated to mimic the neutronic effect, before the TWIST is tested in the Transient Reactor Test Facility (TREAT) at Idaho National Laboratory.